Publications
Filter Total Items: 1994
Postfledging nest dependence period for bald eagles in Florida
We studied the postfledging dependency period in bald eagles (Haliaeetus leucocephalus), a little studied but important period in the life cycle of avian species. Bald eagles in Florida had a postfledging dependency period of 4-11 weeks (15-22 weeks old). The length of the dependency period did not vary by year of study, sex, number of fledgings, timing of fledging, or hatch order (P > 0.05). Mean
Authors
P.B. Wood, Michael W. Collopy, C.M. Sekerak
Phytoplankton assemblages in high-elevation lakes in the northern Cascade Mountains, Washington State, USA
Phytoplankton assemblages in high-elevation lakes of North Cascades National Park Service Complex were studied during the open-water period in 1989. Collectively, 93 taxa were identified in 55 samples from 51 lakes. Based on cell densities, cyanobacteria had the highest relative abundance (36.7 %), followed by chlorophytes (29.8 %), and chrysophytes (19.6 %). Aphanocapsa delicatissima had the high
Authors
Gary L. Larson, C. D. McIntire, R.E. Truitt, W.J. Liss, Robert L. Hoffman, E. Deimling, G.A. Lomnicky
Relationships among environmental variables and distribution of tree species at high elevation in the Olympic Mountains
Relationships among environmental variables and occurrence of tree species were
investigated at Hurricane Ridge in Olympic National Park, Washington, USA. A transect
consisting of three plots was established down one north-and one south-facing slope in
stands representing the typical elevational sequence of tree species. Tree species
included subalpine fir (Abies lasiocarpa), Douglas-fir (Pseu
Authors
Andrea Woodward
Assessing relative abundance and reproductive success of shrubsteppe raptors
From 1991-1994, we quantified relative abundance and reproductive success of
the Ferruginous Hawk (Buteo regalis), Northern Harrier (Circus cyaneus), Burrowing Owl
(Speotytoc unicularia), and Short-eared Owl (Asio flammeus) on the shrubsteppe plateaus
(benchlands) in and near the Snake River Birds of Prey National Conservation Area in
southwestern Idaho. To assess relative abundance, we search
Authors
Robert N. Lehman, L.B. Carpenter, Karen Steenhof, Michael N. Kochert
Field response of tadpoles to conspecific and heterospecific alarm
Many organisms use chemical cues from a variety of sources to mediate predator avoidance. Response to heterospecific alarm cues has been demonstrated for tadpoles within but not among taxa and alarm response behavior has seldom been examined under field conditions. This study examined the response of three sympatric amphibian larvae and predaceous larval Dytiscus sp. (diving beetle) to damage-rele
Authors
M. J. Adams, S. Claeson
Vulnerability of desert biological soil crusts to wind erosion: The influences of crust development, soil texture, and disturbance
Biological soil crusts, consisting of cyanobacteria, green algae, lichens, and mosses, are important in stabilizing soils in semi-arid and arid lands. Integrity of these crusts is compromised by compressional disturbances such as foot, vehicle, or livestock traffic. Using a portable wind tunnel, we found threshold friction velocities (TFVs) of undisturbed crusts well above wind forces experienced
Authors
Jayne Belnap, Dale A. Gillette
Understory vegetation in old and young Douglas-fir forests of western Oregon
We studied understory composition in thinned and unthinned Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)/western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands on 28 sites in western Oregon. These stands had regenerated naturally after timber harvest, 40–70 years before thinning. Commercial thinning had occurred 10–24 years previously, with 8–60% of the volume removed from below with the in
Authors
J. D. Bailey, C. Mayrsohn, P. S. Doescher, Elizabeth St. Pierre, J. C. Tappeiner
Routes and travel rates of migrating Peregrine Falcons Falco peregrinus and Swainson's Hawks Buteo swainsoni in the Western Hemisphere
We describe and compare the migration routes, length of migration, and duration of migration of Peregrine Falcons Falco peregrinus tundrius and Swainson's Hawks Buteo swainsoni in the Western Hemisphere. We radio tracked migrants using the Argos satellite system. Our initial samples were 34 Swainson's Hawks from representative areas of their breeding range, and 61 Peregrine Falcons captured at nes
Authors
Mark R. Fuller, William S. Seegar, Linda S. Schueck
Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir
Genetic implications of natural and artificial regeneration following three regeneration methods (group selection, shelterwood, and clearcut) were investigated in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) using genetic markers (17 allozyme loci). In general, harvesting followed by either natural or artificial regeneration resulted in offspring populations little alt
Authors
W.T. Adams, J. Zuo, J.Y. Shimizu, J. C. Tappeiner
Choosing indicators of natural resource condition: A case study in Arches National Park, Utah, USA
Heavy visitor use in many areas of the world have necessitated development of ways to assess visitation impacts. Arches National Park recently completed a Visitor Experience and Resource Protection (VERP) plan. Integral to this plan was developing a method to identify biological indicators that would both measure visitor impacts and response to management actions. The process used in Arches for in
Authors
J. Belnap
Influence of habitat on behavior of Towndsend's ground squirrels (Spermophilus townsendii)
Trade-offs between foraging and predator avoidance may affect an animal's survival and reproduction. These trade-offs may be influenced by differences in vegetative cover, especially if foraging profitability and predation risk differ among habitats. We examined above-ground activity of Townsend's ground squirrels (Spermophilus townsendii) in four habitats in the Snake River Birds of Prey National
Authors
Peter B. Sharpe, Beatrice Van Horne
The role of special angling regulations in management of coastal cutthroat trout
No abstract available.
Authors
Robert E. Gresswell, R.D. Harding